Dark burning igniter composition



Aug. 30, 1955 R. H. HEISKELL DARK BURNING IGNITER COMPOSITION Filed Dec.1, 1949 PEG. 1.

BURNING RATES OF BISMUTH TRIOXIDE AND MANGANESE MIXTURES BURNING TIME(SECONDS) (COLUMN 1" LONG x 3/8" DIA.)

FIG. 2.

SURVETLLANOE TESTS ON LOOSE POWDER HOURS EXPOSED TO ATMOSPHERE OF l40 FAND 95 /9 R.H.

gwuwvvtob RH. HETSKELL 2,716,599 DARK BURWING TGNTTER COMPGSITIONRaymond H. Heiskell, (Ioinpton, Calif. Application December 1, 1949,Serial No. 130,534 8 Claims. (c1. s2-2 (Granted under Title 35, U. S.Code (1952), sec. 266) This invention relates to an igniting mixture andmore particularly it concerns a dark burning non-flash ignitercomposition adapted to ignite the tracer composition arranged Within theprojectile.

Heretofore tracer ammunition used by our armed forces provedunsatisfactory especially when used in night encounters, in that, underconditions of darkness, the ignition of the igniter composition whichignites the main tracer charge causes a blinding flash and too muchlight streak at the muzzle of the gun, thus illuminating and disclosingthe position of the gun to the enemy and confusing and misleading thegunner or fire director when aiming of the gun is accomplished byobservation of the tracer streak.

Various attempts have been made to produce an igniter for a tracercomposition which burns without any visible flame. The U. S. Patent toStevenson et al. No. 2,115,047 discloses an igniter composition which isof the dark burning type. In my copending application Serial Number35,960 filed June 29, 1948, for Composition for a Tracer Unit and in mycopending application Serial Number 35,961 filed June 29, 1948, for aPyrotechnic Mixture for a Projectile, further compositions are disclosedwhich have the property of burning without visible flame. These priorart compositions, while possessing the desired dark burning qualities,lack to a large degree stability under conditions of high temperatureand high humidity. The compositions of the present invention aredesigned to eliminate the disadvantages inherent in prior artcompositions of the dark burning type, namely, their lack of stabilityunder adverse temperature and humidity conditions.

Accordingly, it is an object of the present invention to provide animproved dark burning non-flash igniter composition which will serve toignite the basic mixture of a tracer shell.

Another object is to provide a new and improved dark burning ignitercomposition for a bright burning tracer composition employed in aprojectile and adapted to delay ignition of the tracer compositiontherein for a predetermined period of time after the projectile has beenfired from a gun and traveled a short distance from the muzzle thereof.

Still another object is to provide a new and improved delay non-flashigniter composition for a tracer ammunition which will not deterioratewhen stored for a long period of time and is not effected by atmosphericcon ditions such, for example, as high temperature and high humidity.

Still another object of the invention is to provide a new and improveddark burning igniter composition which has high stability under adversestorage conditions and which has a relatively fast burning speed whichmakes it suitable for use as an igniter in a high velocity projectile inthat it burns at such a speed as to provide the proper time delaybetween the firing of the projectile and the ignition of the lightemitting tracer composition.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description and by reference to thedrawing in which:

Fig. 1 is a graph illustrating the manner in which the burning speed ofthe composition of the present invention varies in accordance withvarying percentages of the ingredients.

Fig. 2 is a graph illustrating the stability of the composition of thepresent invention.

In accordance with the present invention the new and improved darkburning non-flash igniter composition is adapted to be ignited by thepropellent charge of the projectile as the gun is fired and burn dark orwithout a visible flame therefrom, and to cause ignition of the tracercomposition following a predetermined time delay after ignition of theigniter composition.

In an igniter composition of this type there are three characteristicswhich are essential to its proper functioning.

1. The composition must have the quality of burning without a visibleflame and yet with a flame hot enough to ignite the tracer composition.

2. The composition must burn at the proper speed to give the requiredtime delay between the firing of the projectile and the ignition of atracer composition.

3. The composition should have high stability under adverse conditionsof temperature and humidity to assure that the igniter will functionunder any conditions which might be encountered in combat areas.

The composition of the present invention which combines all three of thedesired characteristics listed above comprises a mixture of bismuthtrioxide as the oxidizing agent, and metallic manganese as the fuel orreducing agent. Optionally, a small quantity of a binder or lubricantmay be employed with the mixture, the lubricant being adapted to makethe loading operation of the mixture easier and eliminate anypossibility of ignition while pressing or consolidating the mixture; anda binder being employed to permit the formation of the powder intopellet form. Graphite forms an excellent lubricant while some substancessuch, for example, as stearic acid perform the function both of alubricant and a binder.

The ingredients of the composition described above may be varied withinthe limits listed below:

Per cent Bismuth trioxide (BizOz) to 45 Manganese (Mn) 15 to 55 Binderor lubricant O to 10 Fig. 1 graphically illustrates the manner in whichthe burning speed of the composition varies as the percentage ofmanganese varies. In compiling the data graphically illustrated in Fig.l, a column one inch long and threeeighths of an inch in diameter wasloaded with a number of mixtures of B1203 and Mn having varyingpercentages of manganese. The exposed top layer of the column of ignitercomposition was ignited by any convenient means, and the time requiredfor the composition to burn to the bottom of the column recorded. Thematerial was loaded into the test cup at a pressure of 40,000 pounds persquare inch. From an inspection of the graph it will be apparent that acomposition of desired burning speed may be selected by varying thepercentage composition of the ingredients. In a composition designed foruseas a tracer igniter, a relatively short burning time is the mostdesirable since the main tracer component, giving a bright visibletrace, must be ignited at a short distance, for example yards, from themuzzle of the gun in order to give the gunner ample opportunity toobserve the trace of the projectile. Thus, the preferred composition ofthe present invention for use as a dark igniter for high velocityprojectile such as the 20 and 40 millimeter type will have the minimumburning time indicated by the graph (approximately two seconds whenloaded as described above) and will have a composition as follows:

Per cent Bismuth trioxide (Bi203) 65 Manganese (Mn) 35 Obviously, othermixtures having slower burning speeds may be used and in some cases maybe desirable when a longer time delay is required. However, when thesecompositions are used as dark burning tracer igniters, fast burningspeeds are required since the time delay between the firing of theprojectile and the ignition of the bright burning main tracer chargewill be in the order of only a fraction of a second. In tests made todetermine the burning speed of various mixtures of bismuth trioxide andmanganese, a column of the igniter composition one inch long wasemployed. As indicated above, in a column of this length the minimumburning speed is tWo seconds. Obviously, shorter time delays areobtained by shortening the length of the column of the ignitercomposition. It the column is made too short, however, the igniter willfunction erratically. Thus, when short time delays are required, a fastburning composition is the most desirable since the length of the columnof igniter composition can be made relatively longer and thus the dangerof erratic behavior when employing columns which are very short will beobviated.

Another preferred composition, which has the desired burningcharacteristics and which employs graphite as a binder is as follows:

Per cent Bismuth trioxide (BiaOz) 63 Manganese (Mn) 35 Graphite 2Referring now to Fig. 2 which illustrates the high stability of thecomposition of the present invention under severe conditions oftemperature and humidity, curve A represents the curve developed by acomposition compounded according to the present invention andcomprising:

Per cent Bismuth trioxide (Bi203) 65 Manganese (Mn) 35 Curve Brepresents the curve developed by a composition similar to thatdescribed in my copending application Serial No. 35,960, above referredto, and having the following composition:

Per cent Barium peroxide (BaOz) 76 Antimony sulphide (SbzSg) 23 Graphite1 Curve C represents the curve developed by another composition similarto that described in my copending application Serial No. 35,960 andhaving the following composition:

Per cent Barium peroxide (BaOz) 78.4 Antimony sulphide (SbzSs) 18.4Graphite 1.0 Magnesium (Mg) 2.2

The last two compositions are both dark igniter compositions for tracerunits which were developed by me prior to the development of thecomposition of the present invention. These compositions possess thedesirable qualities of burning without a visible flame and yet with aflame hot enough to ignite the tracer composition, and of burning at theproper speed to give the required time delay between the firing of theprojectile and the ignition of the tracer composition, but lack thethird desideratum, namely stability under adverse conditions oftemperature and humidity. These compositions will function effectivelyafter long periods of storage if they have been carefully sealed, but ifaccidentally or otherwise exposed to the atmosphere they will soon losetheir sensitivity and fail to function.

in making the tests, the results of which are graphically illustrated inFig. 2, the above compositions, in the form of loose powder, wereexposed for a number of hours to a temperature of 140 Fahrenheit and ata relative humidity of Periodically, samples of the above compositionswere removed from the testing chamber and loaded into testing cups atpressures of 40,000 pounds per square inch and ignited and the burningtime clocked. As can be seen clearly by observation of curve A, thecomposition of the present invention burned at almost the same speedafter over hours of exposure. The first of my prior compositions, namelythat which developed curve B, began to lose its burning speed veryquickly. in the tests, after four hours of exposure its burning time hadrisen from 2.8 seconds to 4.4 seconds and after 24 hours exposure thiscomposition failed to ignite at all. The composition which developedcurve C also rapidly underwent a decrease in burning speed. From aburning time at 0 hours of exposure of two seconds, its burning timeincreased to 10.4 seconds after 24 hours of exposure; and after 48 hoursof exposure this composition failed to ignite at all. It can readily beseen that the composition of the present invention has a very markedstability under conditions of high temperature and high humidity andrepresents a marked improvement over prior compositions.

In preparing the ingredients comprising the delay nonflash ignitermixture of the invention it has been found that the most satisfactoryresults are obtained when the bismuth trioxide and manganese are of sucha particle size as to pass through a U. S. standard sieve, mesh size Toinsure such a particle size, the ingredients are first sifted. Whensifting of the ingredients has been completed the ingredients are thenthoroughly mixed in any suitable manner but preferably by placing themin a mixing churn, the churn being of any type suitable for the purposesuch, for example, as the type known in the trade as the Abbe mixerchurn. The time period required to mix the aforesaid ingredientsthoroughly when the churn is set in operation is approximately 30minutes.

A small percentage of graphite or stearic acid may be added to themixture to reduce the frictional sensitivity of the particles of whichthe delay non-flash igniter is composed, sufliciently low to preventpremature detonation of the mixture during pressing thereof into thetracer cavity of the projectile or when consolidating the mixture intopellet form, the stearic acid being adapted to act as both a lubricantand binder.

In loading the delay non-flash igniter mixture into the tracer cavity ofthe projectile it has been found that the best result was obtained whenthe mixture was pressed into the cavity at a pressure of 10,000 to40,000 p. s. i. If desired the mixture may be pressed into pellets at apressure sufiicient to consolidate the mixture whereupon a combinationbinder and lubricant is employed therewith such, for example, as theaforesaid stearic acid. In loading the delay non-flash mixture in pelletform into the tracer cavity of the projectile the pellet is pressed inabutting engagement with the tracer mixture at a pressure in theneighborhood of 40,000 p. s. i.

From the foregoing description it will be understood that a delaynontracing mixture for tracer ammunition has been compounded andconstructed which is sufliciently stable to permit the tracer ammunitionto be stored over a long period of time and is sufiiciently sensitive tobe ignited by the propcllent charge as the projectile is fired from thegun and which will burn without a visible flame so as not to disclosethe gun position or blind the gunner and which burns sufi'lcientlyrapidly and with a flame hot enough to initiate ignition of the tracermixture after a predetermined time delay.

Obviously, the composition of the present invention may be applied toother uses than as an igniter composition for a tracer unit wherecharacteristics similar to those possessed by the composition of theinvention are desirable, and it is apparent that many modifications andvariations of the present invention are possible in tlz: light of theabove teachings. It is therefore to be understood that within the scopeof the appended claims the invention may be practiced otherwise than asspecifically described.

The invention hereindescribed and claimed may manufactured and used byor for the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A highly stable dark burning igniter composition comprising from 85to 45% of bismuth trioxide and from 15 to 55% manganese.

2. A highly stable dark burning igniter composition comprising from 85to 45% of bismuth trioxide, from 1.5 to 55% manganese, and up to of abinder.

3. A highly stable dark burning igniter composition comprising from 85to 45% of bismuth trioxide, from to 55% manganese, and up to 10% of alubricant.

4. A highly stable dark burning igniter composition comprising about 65%of bismuth trioxide and about of manganese.

5. A highly stable dark burning igniter composition comprising about 63%of bismuth trioxide, about 35% of manganese, and about 2% graphite.

6. A highly stable dark burning igniter composition comprising from 85to of bismuth trioxide, from 15 to of manganese and up to 10% of stearicacid.

7. A highly stable dark burning igniter composition comprising from to45% of bismuth trioxide, from 15 to 55 of manganese, and up to 10%graphite.

8. A highly stable dark burning igniter composition comprising about 63%of bismuth trioxide, about 35% of manganese, and about 2% of stearicacid.

References Cited in the file of this patent UNITED STATES PATENTS

2. A HIGHLY STABLE DARK BURNING IGNITER COMPOSITION COMPRISING FROM 85TO 45% OF BISMUTH TROXIDE, FROM 15 TO 55% MANGANESE, AND UP TO 10% OF ABINDER.
 3. A HIGHLY STABLE DARK BURNING IGNITER COMPOSITION COMPRISINGFROM 85 TO 45% OF BISMUTH TROXIDE, FROM 15 TO 55% MANGANESE, AND UP TO10% OF A LUBRICANT.